title: Dynamic aspects of the incorporation of proteins into biological membranes.
abstract: The contributions of intramembranous and extramembranous segments of transmembrane proteins to frictional forces have been studied by covalently attached 14N- and 15N-indane dione and maleimide spin labels using saturation transfer electron spin resonance spectroscopy. The role of molecular size and membrane viscosity is discussed in determining rotational mobilities of proteins. By comparing the measured rotational correlation times with the predictions of hydrodynamic models the aggregation states of transmembrane proteins is estimated. On increasing the viscosity of the aqueous phase by polyols the viscous drag of the extramembranous segments of proteins is increased and from systematic hydrodynamic measurements the size of the protruding segments can be estimated. The role of slowed molecular diffusion is briefly discussed in the inhibition of enzymatic activity.
authors.affiliation: Institute of Biophysics, Biological Research Centre, Szeged, Hungary.
authors.forename: L I
authors.initials: LI
authors.lastname: Horváth
authors.forename: M
authors.initials: M
authors.lastname: Török
authors.forename: K
authors.initials: K
authors.lastname: Hideg
authors.forename: L
authors.initials: L
authors.lastname: Dux
mesh_terms: D001692:Biological Transport; D000252:Calcium-Transporting ATPases / Q000737:chemistry; D002463:Cell Membrane Permeability; D003497:Cyclic N-Oxides; D004058:Diffusion; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation / Q000502:physiology; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism*; D007189:Indans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D012399:Rotation; D013113:Spin Labels; D013997:Time Factors; D014783:Viscosity
chemical_list: D003497:Cyclic N-Oxides; D006454:Hemoglobins; D007189:Indans; D008565:Membrane Proteins; D013113:Spin Labels; C003028:N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)iodoacetamide; C001445:1,3-indandione; D000252:Calcium-Transporting ATPases